Uncoupler devices for miniature railroad cars are generally permanently attached to a piece of miniature railroad track which is part of the miniature railroad track circuit. In order to move the uncoupler from one location to another within the track circuit or system, it is necessary to partially disassemble the system to remove the piece of track with the uncoupler attached and install it elsewhere in the circuit. This is a relatively time consuming and cumbersome procedure which limits the versatility of the track operator in uncoupling cars at various places within the circuit.
Most uncoupling devices have several moving parts and are manually operated, or by remote control. To avoid derailing of the cars, these uncouplers must be actuated while the particular coupler of the railroad car is directly over the uncoupling apparatus. This has a disadvantage of having to time the precise moment to activate the uncoupler in order to achieve the desired separation in the chain of miniature railroad cars.
Most miniature railroad uncouplers have the additional disadvantage that they cannot be used with curved track. Miniature railroad systems therefore are usually designed with the constraint that all desired uncoupling will have to be done in a straight portion of the track system.
Most uncoupling devices for miniature railroad car uncouplers of the type discussed here are relatively expensive due to the number of moving parts involved and the fact that it must be manufactured permanently attached to a piece of railroad track. Further, in order to have a great deal of versatility in the miniature railroad system, a large number of these permanent installations must be employed.
Since the introduction of Rapido type couplers, a satisfactory portable uncoupler has not been available. Portable uncoupling devices for other coupling systems have been proposed, but none has been able to overcome the problems described above and still function with the Rapido coupler design. For example, the portable uncoupler described in the Pat. No. 2,263,959, by J. N. Tyler, entitled "Car Coupling and Uncoupling Mechanism," utilizes a raised resilient strap attached to a portable base. However, the strap is designed to deflect only a small amount. Used with the Rapido coupler, the strap would have to be raised sufficiently to lift the coupler pins, but be able to deflect enough to allow the cars' axles to pass over without derailing. The relatively large amount of deflection required causes the resilient strap to "pop" or "oil can." This popping results in erratic performance of the uncoupler and can cause derailment of the miniature railroad cars.